Books: Reason's Playboy

THE EMBATTLED PHILOSOPHER (442 pp.) —Lester G. Crocker—Michigan State College ($6.50).

French Philosopher Denis Diderot had the intellectual brilliance that sparkled in an 18th century drawing room, but he sometimes found less conventional ways to display his native gifts. When a lady painter who was doing his portrait objected that his clothes hid his neck, the eminent thinker silently retired behind a curtain and reappeared a moment later "as naked as a worm."

"I should never have dared to suggest it," the lady painter fluttered, "but you have done well and I thank you."

Many a woman probably said the same thing to dashing Denis Diderot, but for another reason. "Look for women who won't make you sigh too long," young Denis advised. "They amuse as much as the others; they take less time; you possess them without worries and leave them without regrets." Up in Paris from the provinces, where he almost took vows of chastity and became a priest, Diderot followed his own advice and lived the left-bank vie de Bohéme, made up of much talk, not enough food and more than enough love.

It was then, as a student, that Diderot caught that insidious 18th century disease: a chronic high fever to know everything. The Embattled Philosopher tells the story of how Denis Diderot, philosopher, encyclopedist, playwright, novelist, art critic, conversationalist and lover, came to personify the French 18th century, and how he created the intellectual Trojan horse that led to the downfall of the Bourbon monarchy. It is the first biography of Diderot to appear in English in three-quarters of a century, and it is a good one. Author Lester G. Crocker, a Goucher College professor and former movie writer, knows how to blow the dust off his subject, and bring both an 18th century personality and his ideas to life.

The Big Idea. Papa Diderot objected to his son's studies, but let him be until he learned that Denis planned to marry. He then had the young lover imprisoned in a monastery with a lettre de cachet. But Denis escaped, dashed after his chérie, married her and almost immediately stopped loving her. There followed a succession of mistresses. The first was expensive and forced him to write his early books about philosophy to provide her with pocket money. The second was Sophie, Diderot's great love. "Ah," he rhapsodized, "what a woman! How tender she is, how sweet, honest, delicate, sensible!" But she was hardly a beauty. At 38, she was well past the first blush of youth. Nevertheless he wrote her lovingly: "My dear, I kiss your brow, your eyes, and your dried-up little face . . ."